Responsa for Taanit 61:4

אמר רב מנשיא וקרו ליה יום תבר מגל מכאן ואילך דמוסיף יוסיף ודלא מוסיף (יאסף) (תני רב יוסף) מאי יאסף אמר רב יוסף תקבריה אימיה:

'And dealest kindly': Because permission was granted for their burial. Rabbah and R'Joseph both said: It is the day on which [every year] they discontinued to fell trees for the altar.<span class="x" onmousemove="('comment',' Undried wood harbours woodworms and this makes the wood unfit for the altar. After the fifteenth of Ab the rays of the sun are not sufficiently strong to dry the fresh-cut logs and therefore the felling of trees for the altar was discontinued as from this date. Cf. Mid. II, 5.');">⁴</span>

Shut min haShamayim